Alternative methods of traffic characterization in flexible pavement design

Abstract

Abstract

This paper investigates the way in which traffic data are used in flexible pavement design and analysis procedures. A deterministic long-term pavement performance model (LTPPM) is used to calculate flexible pavement damage caused by trafficking from three realistic fleets of commercial vehicles. The fleets have been modelled using seven-axle group models representing steer axles, drive axles (single or tandem) and trailer axles (tandem or tridem) with either steel suspensions or air suspensions. Results are compared with the calculated flexible pavement damage caused by a fleet of 80 kN standard axles and predictions from the currently used method of traffic characterization for UK pavement design procedures. Results show that pavements that fail by rutting last longer when trafficked by the realistic vehicle fleets compared with the fleet of 80 kN standard axles whereas the pavements that are predicted to fail by fatigue last longer when trafficked by the fleet of 80 kN standard axles. Results also show that current UK pavement design procedures are more sensitive to differences in the vehicle fleet compared with LTPPM predictions.